HYBRID SIMULATION OF PARTICLE ACCELERATION CAUSED BY MAGNETIC RECONNECTION
磁场重联中离子轨道的混合模拟研究

Applying a 2.5-D hybrid simulation, we have studied the particles acceleration caused by magnetic reconnection. The results show that the reconnection process will not only heat all the particles, but also accelerate a few particles to comparatively high velocities (about 2.0v A). Such selective accelerating makes the velocity distribution of all particles change from the Maxwellian distribution to a shell or quasi-shell distribution. In addition, this shape varies with the change of particle positions. In order to study the accelerating process occurring near the X-type neutral point, we have observed the time-variation of velocities and positions of selected particles. Among the particles are flowed out inside the reconnection region, some are trapped in the magnetic mirror, with a convolution radius that outsteps the width of the reconnection region. These particles can thus construct the low speed part of the fluid near the boundary of out flow regions. On the other hand, there are three kinds of drifting trajectory of particles entering the reconnection region beside the X-type neutral point: flee along the field lines, be trapped in the magnetic mirrors, and traverse the local field lines. The ratios of particles undergoing the three kinds of trajectory are about 70%, 20%,10%, respectively.